The components of high-temperature mechanical systems, such as, for example, gas-turbine engines, typically operate in severe environments. For example, hot section components of gas turbine engines, e.g., turbine blades and/or vanes, exposed to hot gases in commercial aeronautical engines may experience surface temperatures of greater than 1,000° C. Ceramic or ceramic matrix composite (CMC) materials may be useful in such high temperature environments, but some ceramics or CMCs may react with some elements and compounds present in the operating environment or certain layers or portions of the substrate component. Reaction with such elements or compounds may result in degradation of the ceramic or CMC substrate leading to a reduced lifespan. In some examples, a ceramic or CMC substrate may be coated with an environmental barrier coating, which may reduce exposure of the substrate to elements and compounds present in the operating environment of high temperature mechanical systems.